System and method for neuromuscular reeducation

ABSTRACT

A system and a method that promotes the restoration of physical functions of the neuromuscular system by incorporating into one device the treatment modalities of biofeedback based repetitive practice, includes an actuator, a joint position measurement system, a force sensing measurement system, an EMG measurement system, a neuromuscular low-level stimulation system, a controller, and a display device.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/430,700 filed Dec. 4, 2002, whose entire contents are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention broadly relates to bio-monitoring in patients, anddeals more particularly with a system and a method for implementing aprotocol for restoring physical functions of the neuromuscular systemthrough bio-feedback.

2. General Background and State of the Art

Many people have movement disabilities caused by disease or injury.Among the causes are cerebrovascular accident or stroke (CVA), traumaticbrain injury, multiple sclerosis, spinal cord injury and Parkinson'sdisease. Stroke is the leading cause of disability in the United Stateswith at least 700,000 new cases each year. Over half of these peoplehave residual physical disability. Current stroke therapy islabor-intensive and costly. Often insurance does not cover the cost offull therapy. One estimate is that the United States spends $30 billionper year to take care of stroke survivors. Seventeen billion dollars ofthis cost is direct medical expenditures and thirteen billion dollarsrepresent an indirect cost due to lost productivity. Another estimate isthat the total direct and indirect costs of stroke are $43.3 billion peryear. The number of strokes is projected to increase because of theincrease in the over 50 “baby boom” population. Also, new pharmaceuticaltreatments for stroke are projected to increase the number of patientssurviving a stroke and increase the percentage of stroke survivorsrequiring rehabilitation. Therefore, it is not surprising that a recentestimate indicates the prevalence of stroke will more than double overthe next 50 years.

Following a stroke, the initial treatment is to stabilize the patient.This usually occurs in an emergency room and critical care unit.Following stabilization, the patient is typically transferred to ahospital rehab unit. The time in a rehab unit has been significantlyreduced in recent years by the pressures of health care reimbursementbut could be as much 14 days. Because of the reduced time, very littletherapy aimed at restoring function is applied. Patient activitiesinvolve learning toileting, transfers between locations and how toperform functions with the unaffected limb which reinforces learnednon-use and hinders restoration of function of the affected limb. Thelevel of disability and availability of health care funds determineswhere the patient goes following discharge from the rehab unit. The mostseverely afflicted go to a nursing home. Some patients receivecomprehensive treatment in Day Treatment facilities, whereas somepatients go to out-patient facilities for treatment of specificfunctional losses, while others receive home health treatment fromvisiting therapists.

Because of health care reimbursement reductions, therapy time for strokepatients has been significantly decreased. Currently, a majority of timespent in therapy post-stroke concentrates on helping a patient adapt totheir disability by teaching toileting skills and transfers. Aconsequence of this treatment is the emergence of “learned nonuse” thathinders the restoration of available function. Most currentrehabilitation therapies are administered on a spaced basis. Recently,concentrated therapies have been developed that improve function in CVApatients by reversing the effects of “learned nonuse”. Animal studiessuggest that learned nonuse is established immediately after the initialorganic damage. A patient is punished for trying to use the affectedlimb and is rewarded for using other parts of the body. Over time,healing of the organic damage occurs but the suppression of use learnedin the acute phase remains in force. Also, many of the therapies thathave been shown to be effective in restoring function involve massedpractice. Physical Therapy training techniques have been used byresearchers. Significant improvement in limb function was obtained inchronic CVA patients.

Training techniques based on electromyographic (EMG) biofeedback improvemotor ability of chronic CVA patients, as demonstrated by some studies.Repetitive concentrated practice produced large therapeutic effects forlower limb function. Researchers have also systematically studied avariation of forced use of hemiplegic extremities which has been labeledConstraint-Induced (CI) Movement Therapy. Some of these experimentscompared several massed therapy techniques and all showed very largeincreases in limb use over the treatment period.

Two very sophisticated robot systems are being developed for treatmentand evaluation of CVA patients which have shown some effectiveness intreatment of CVA patients and have developed very useful data forunderstanding recovery mechanisms; however, the current cost of thesesystems precludes their widespread clinical use.

Other studies have shown that measured EMG can be used to triggerneuromuscular electrical stimulation in restoring function to CVApatients. However, the discomfort of surface neuromuscular stimulationsignificantly limits the clinical implementation of this modality forpersons with hemiplegia. EMG biofeedback treatment of stroke patientshas also shown some success. This treatment uses surface electrodes tocapture the electrical activity of a selected muscle group. Anelectronic unit converts the signals into visual or audio informationfor the patient. This information is used by the patient to augment ordecrease muscle activity.

Accordingly, what is needed is a system and a method that promotes therestoration of physical functions of the neuromuscular system byincorporating into one device, the treatment modalities of repetitivepractice, and force and EMG biofeedback. Furthermore, the system shouldbe inexpensive, portable, comfortable, and easy to use either by thepatient or by a therapist.

INVENTION SUMMARY

The system according to the present invention will assist in therapy bysupplying increased amounts of information to the physician/therapistwhile reducing the amount of patient contact time. The system isadaptable to accommodate the changing paradigm of cerebrovascularaccident (CVA) rehabilitation service delivery and to assist in studiesdesigned to refine therapy protocols.

Accordingly, in one aspect of the invention, the system forneuromuscular function reeducation and restoring physical function of aneuromuscular system, associated with a joint in a patient, includes atleast one sensor for measuring an electrical signal associated with anagonist muscle in the neuromuscular system of the patient. Theelectrical signal associated with the agonist muscle is used to providevisual feedback for controlling the joint extension and flexion therebyenabling reeducation and restoration of the physical function of theneuromuscular system.

In another aspect of the invention, the system for neuromuscularfunction reeducation and restoring physical function of a neuromuscularsystem, associated with a joint in a patient, includes at least onesensor for measuring an electrical signal associated with an agonistmuscle in the neuromuscular system of the patient, at least one sensorfor measuring an electrical signal associated with an antagonistresisting muscle. The electrical signal associated with the agonistmuscle and the electrical signal associated with the antagonistresisting muscle are combined to form a net signal which is used toprovide visual feedback for controlling the joint extension and flexionthereby enabling reeducation and restoration of the physical function ofthe neuromuscular system.

In another aspect of the invention, the system for neuromuscularfunction reeducation and restoring physical function of a neuromuscularsystem, associated with a joint in a patient, includes at least onesensor for measuring an electrical signal associated with an agonistmuscle in the neuromuscular system of the patient, at least one sensorfor measuring an electrical signal associated with an antagonistresisting muscle, at least one electrode for providing a low-levelneuromuscular stimulation to the neuromuscular system. The electricalsignal associated with the agonist muscle and the electrical signalassociated with the antagonist resisting muscle can be viewed separatelyor combined to form a net signal which is used to provide visualfeedback, the visual feedback and the low-level neuromuscularstimulation being used for controlling the joint extension and flexionthereby enabling reeducation and restoration of the physical function ofthe at least one neuromuscular system.

In another aspect of the invention, the system for neuromuscularfunction reeducation and restoring physical function of a neuromuscularsystem, associated with a joint in a patient, includes at least onecontinuous passive device for allowing the extension and flexion of thejoint, wherein the continuous passive device permitting self-actuationof the neuromuscular system, at least one force sensor for measuring aparameter indicative of resistance of an antagonist resisting muscle,the antagonist resisting muscle associated with the neuromuscularsystem. The parameter which indicates the resistance of the antagonistresisting muscle is used for controlling the joint extension and flexionthereby enabling reeducation and restoration of the physical function ofthe at least one neuromuscular system.

In another aspect of the invention, the system for neuromuscularfunction reeducation and restoring physical function of at least oneneuromuscular system, associated with an at least one joint in apatient, includes: (i) a motion causing device adjacent to the joint,the motion causing device permitting self-actuation of the neuromuscularsystem; (ii) at least one force sensor for measuring a parameterindicative of the muscle resistance; (iii) at least one joint positionsensor for measuring joint movement; (iv) at least one neuromuscularelectrical stimulating (NMES) system; (v) an electronic memory systemthat stores information of the patient; (vi) at least one EMG sensor formeasuring the electrical activity of the neuromuscular system; and (vii)a controller that implements a protocol for controlling the joint motionbased on the measurements from the sensors thereby restoring physicalfunction of the neuromuscular system associated with the joint.

In one embodiment of the present invention, the motion causing devicecould be an inflatable device, such as a pneumatic air-muscle, havingtwo ends, wherein one end is connected to a distal element of the jointand the other end to a proximal element of the joint. Such a device hasthe property that increasing the diameter, by supplying pressurized airfor it to inflate, causes it to shorten thereby causing the joint topivot about at least one axis. Like human muscle, this device hasspring-like characteristics, is flexible, and is lightweight. Moreover,the force-deflection characteristics can be made substantially similarto those of human muscle.

In conjunction with the system for neuromuscular function reeducationand restoring physical function of at least one neuromuscular system,the present invention includes a method for implementing a protocol forrestoring physical function of the neuromuscular system associated withan at least one joint in a patient. This method comprises: (i) measuringa first signal indicative of the activity of a muscle, in theneuromuscular system, through an EMG sensor; (ii) measuring a secondsignal indicative of the joint motion through a joint position sensor;(iii) measuring a third signal indicative of the muscle resistancethrough a force sensor; (iv) mapping the measured signals to at leastone parameter; and (v) controlling the air level in an inflatable device(such as the pneumatic air-muscle) in order to optimize the parameterfor restoring physical function of the muscle, in the neuromuscularsystem, associated with the joint in the patient.

Furthermore, although repetitive task practice therapies have been shownto be effective, a significant number of stroke survivors haveinsufficient hand motion to participate fully in these activities.Studies have shown that the Tonic Vibration Reflex (TVR) lowersrecruitment thresholds of agonist muscle groups and inhibit activationof antagonistic muscle groups. This tonic reflex mechanism of theagonist muscle is stimulated by prolonged vibration of its tendon. Thesetrains of vibration to a tendon of a receptor-bearing muscle stimulatehuman spindle primary afferents which cause autogenetic musclecontraction. For example TVR activation of wrist and finger muscles canbe used to enhance the motion and functionality of stroke patients thathave high flexor muscle tone and low extensor motion. Thus anotheraspect of the invention incorporates a vibrator to stimulate the TVR.

Thus, in another aspect of the invention, the system for neuromuscularfunction reeducation and restoring physical function of a neuromuscularsystem, associated with a joint in a patient, includes at least onesensor for measuring an electrical signal associated with an agonistmuscle in the neuromuscular system of the patient, at least one sensorfor measuring an electrical signal associated with an antagonistresisting muscle, at least one vibrator to excite the TVR. Theelectrical signal associated with the agonist muscle and the electricalsignal associated with the antagonist resisting muscle can be viewedseparately or combined to form a net signal which is used to providevisual feedback, the visual feedback and the low-level neuromuscularstimulation being used for controlling the joint extension and flexionthereby enabling reeducation and restoration of the physical function ofthe at least one neuromuscular system.

The above and other objects, features, and advantages of the presentinvention will become apparent from the following description read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one embodiment of the motion causing device, which is theair-muscle described herein, attached to the proximal forearm along withvarious sensors and a controller box;

FIG. 2 depicts an exemplary procedure for attaching EMG electrodes formeasuring joint extensor activity;

FIG. 3 shows one embodiment of the motion causing device, which is theair-muscle described herein, in at least two operational modes, namelythe deflated mode and the inflated mode which flexes and extends,respectively, the wrist joint;

FIG. 4 shows another embodiment of the motion causing device, which isthe air-muscle described herein permitting the wrist joint to be inflexion, neutral, and extended position respectively;

FIG. 5 is a block diagram showing one embodiment of the present systemfor neuromuscular function reeducation and restoring physical functionof at least one neuromuscular system;

FIG. 6 shows the pivot points and trajectory taken by the motion causingdevice, such as an air-muscle, according to one aspect of the presentinvention;

FIG. 7 shows the pivot points and trajectory taken by the motion causingdevice, such as an air-muscle, according to another aspect of thepresent invention;

FIG. 8 is a flow chart depicting one embodiment for the protocol forneuromuscular function reeducation and restoring physical function of atleast one neuromuscular system;

FIG. 9 is one embodiment of the invention using a continuous passivemotion (CPM) device in conjunction with an air-muscle device;

FIG. 10 is an alternative embodiment, with reduced linkages, showing thepivot points and trajectory taken by the air-muscle;

FIG. 11 is yet another embodiment, with reduced linkages, showing thepivot points and trajectory taken by the air-muscle;

FIG. 12 is an initial state of the air-muscle device used in conjunctionwith a robotic system for providing assistive training;

FIG. 13 is an intermediate state of the air-muscle device used inconjunction with a robotic system for providing assistive training;

FIG. 14 is a final state of the air-muscle device used in conjunctionwith a robotic system for providing assistive training; and

FIG. 15 is an exemplary plot depicting the torque calibration curves fortwo strap conditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and in particular to FIG. 1, there isshown motion causing device or an actuator 10 attached to the proximalforearm 12 along with various sensors 14,15 for monitoring activityalong the proximal forearm 12 and the at least one joint 16, at leastone electrostim electrode 22 for providing a low-level neuromuscularstimulation, and a controller box 18 with a display port 20 forproviding visual feedback for a patient/therapist. The system shown inFIG. 1 is used for neuromuscular function reeducation and restoringphysical function of at least one neuromuscular system.

It is important that the actuator 10 permit relative motion between theproximal and distal portions of the joint 16 in a manner to minimize anyhindrance or interference with any motion generated by the patient'sneuromuscular system.

In one embodiment, the actuator 10 is a pneumatically operatedair-muscle. A prior art artificial muscle device exhibits many of theproperties of human muscle. The artificial muscle device consists of anexpandable internal bladder (e.g., a rubber tube) surrounded by abraided shell. When the internal bladder is pressurized, it expandsradially against the braided shell causing the muscle to contract.Braided finger traps used to hold fingers on traction devices contractradially when pulled. The air-muscle, according to one embodiment in thepresent invention, works in the same manner but in the oppositedirection (i.e., increasing the diameter causes it to shorten). Likehuman muscle, the device has spring-like characteristics, is flexible,and is lightweight. The force-deflection characteristics can be madesimilar to those of human muscle. Pressurized air canisters oraccumulators that are recharged by air compressors can be used as asource for supplying air to the air-muscle. Major advantages of the airmuscle are its flexibility and ease of adaptation to address thespecific loss of function exhibited by a patient. Additionally, thedevice of the preferred embodiment has three times the pull force of anair piston of the same cross sectional area. The utility of this deviceresides in its unique combination of attributes: low cost, light-weight,low profile, and low noise operation.

The sensors include at least one joint position sensor 15 for measuringjoint movement, at least one force sensor 48 (shown in FIG. 5A) formeasuring a parameter indicative of the muscle resistance, at least oneEMG sensor 14 for measuring the electrical activity of the neuromuscularsystem. Furthermore, there is at least one neuromuscular electricalstimulating (NMES) device, such as an electrostim electrode 22, forproviding low-level neuromuscular stimulation.

The controller box 18, connected through cable 24 to the air-muscle 10,includes electronics (i) for recording and displaying 20 measurementsobtained through various sensors 14, 15, and (ii) for controlling theair-muscle 10 operation (e.g., by controlling the supply of air into themuscle). This controller box 18 is a self-contained, mobile device thatprovides sensory (e.g., visual) feedback of wrist and finger position,EMG extensor activity and wrist flexor resistive torque. Alternatively,the sensory feedback could be provided through tactile sensing throughpiezoelectric transducer induced vibrations on the skin, or throughaudio signals (e.g., beeps through an auditory display). The firmware inthe microprocessor of the controller system 18 has been designed to bewell-structured using object-oriented programming techniques. Use ofthese techniques yields more reliable code having fewer discrepanciesand problems. The controller box 18 is shown as a separate device,however it is to be understood that the box could be a sleeve wrappedaround the arm of a patient and as shown in FIG. 2.

FIG. 2 depicts an exemplary procedure for attaching at least one EMGelectrode 15 for measuring joint extensor activity (also known as theagonist muscle activity). Closely spaced surface electrodes are used tomeasure joint extensor EMG activity. The location of the EMG electrodes15 is determined for each patient by the therapist. The skin may berubbed several times with alcohol soaked gauze pads. The EMG electrodeoutput is used to measure the relative recruitment of selected extensormuscles and may be used to feedback the information to the patient toreinforce correct recruitment. Session to session variation in EMGvalues may be recorded for monitoring patient performance and/orcompliance. The EMG sensor may be used for measuring the electricalactivity of an agonist muscle (e.g., the extensor muscle) and/or anantagonist resisting muscle (e.g., the flexor muscle) in theneuromuscular system of a patient. Two measuring channels may be used tocapture EMG activity of the muscle sets of the neuromuscular system.

The air-muscle is supplied by compressed air by means of a source (FIG.5, 42), and the air supply may be controlled by the controller 18 thatincludes a microprocessor (FIG. 5B) for controlling at least one valve(FIG. 5C, 46) that controls the supply of pressurized air to theair-muscle.

In one embodiment of the present invention, as shown in FIG. 3, one endof the air-muscle 10 is connected to a distal element 34 of the wristjoint 16 and the other end of the air-muscle 10 is connected to aproximal element 32 of the wrist joint 16. Activation of the air muscle10, by inflating it through a supply source 42 (FIG. 5C) of air, maycause the joint to pivot about at least one axis and causing the jointto go from a flexed position to the extended position as shown in FIG.3. As an example, this could be achieved by means of rotation of a barthat extends the wrist and operates a mechanism that extends the fingersand wrist between a flexed, neutral, and extended positions as shown inFIG. 4. An optional data port 36 may be provided for downloading storedinformation from the memory 50 (FIG. 5) of controller 18 to a PC (notshown).

Now referring to FIG. 4, an alternative embodiment of the presentinvention is shown therein. Specifically, the wrist joint is shown inthree states (flexion, straight, and extended). The air-muscle device 10(shown with a braided type covering), having strap 330 for permittingair from a source 42, is connected at one end to the forearm supportstructure 300 via connector 326. The support 300 wraps around theforearm and is held in place by means of straps 322. The other end ofthe air-muscle 10 is connected to a bar 324 which also provides a pulleyfor the extension strip 336. One end 320 of the strip 336 is connectedto a bar 338 with a corresponding joint 332. The other end of strap 336is attached to the support structure 300. The joints, 342 and 340, ofthe support structure 300 are positioned substantially adjacent theknuckles 344 and the finger joints 346, respectively, of the patient'shand. The structure 300 may also include tubes 352 for allowing thefinger ends to be housed.

With regards to the operation of the device in FIG. 4, shown therein arethree states that the wrist joint may achieve: (i) flexion, (ii) normal,and (iii) extension. Clearly, the device permits a very high number ofstates intermediate to the states shown in FIG. 4. The air-muscle 10extends, relatively, in length, upon deflation (as shown in the topfigure of FIG. 4), which causes the bar 338 to rotate/pivot clockwise(looking from the top and as depicted by the arrow 400) about joint 310.This causal effect is established by means of the strip 336 thatconnects the bar 338 to the air-muscle 10. This pivot action of the bar338 causes the wrist to achieve the flexion state. Furthermore, rotationof the joints 342 and 340 may allow the knuckle joints and the fingerjoints to assume curled/retracted positions.

The air-muscle 10 shortens, relatively, in length, upon reasonableinflation (as shown in the middle figure of FIG. 4), which causes thebar 338 to rotate/pivot counter-clockwise (looking from the side and asdepicted by arrow 420) about joint 310. This causal effect isestablished by means of the strip 336 that connects the bar 338 to theair-muscle 10. This pivot action of the bar 338 causes the wrist toachieve the normal or straight state. Furthermore, rotation of thejoints 342 and 340 may allow the knuckle joints and the finger joints toassume substantially straightened positions.

The air-muscle 10 shortens, relatively, much more in length, upon ahigher degree of inflation (as shown in the bottom figure of FIG. 4),which causes the bar 338 to further rotate/pivot counter-clockwise(looking from the top and as depicted by the arrow 440) about joint 310.This causal effect is established by means of the strip 336 thatconnects the bar 338 to the air-muscle 10. This pivot action of the bar338 causes the wrist to achieve the extension state. Furthermore,rotation of the joints 342 and 340 may allow the knuckle joints and thefinger joints to assume substantially extended positions.

Joint extension position or displacement is measured by the at least onejoint position sensor 15, such as a potentiometer, that is incorporatedin the motion causing device. Resistance to extension, that may be dueto the antagonist resisting muscle, is measured by the at least oneforce sensor 48 (FIG. 5A), such as a force sensitive resistors (FSRs),that is placed on the device. The FSR output is a measure of theresistance of finger and wrist flexor muscles. Alternatively, theresistance to extension may be measured by at least one EMG sensor.Alternatively, the resistance to extension may be determined bymeasuring the maximum extension of a patient's hand under a specifiedactivation pressure. The compliant property of the air muscle allows thelack of full extension to be calibrated versus the resisting load ortorque.

If force sensors are used, the at least one force sensor 48 (i.e., theFSR) is calibrated after each device is assembled. A load cell (notshown) is inserted between an activation bar on the device and muscle.The mechanism is fixed in six different degrees of flexion-extension.The output of the FSR may be compared to the load cell output. Thetorque about the joint at each wrist position is calculated bymultiplying the muscle force by the distance to the line of action ofthe air muscle.

As mentioned above in paragraph 44, the force sensing aspect may besimplified by simply measuring the performance of the air muscle.Specifically, when the air muscle is pressurized, external loads causeit to extend. Thus, the amount of extension caused by the resistance ofspastic resisting muscles may be sufficiently large to be measured withthe joint position potentiometer. The calibration of the amount oflengthening of the muscle may be achieved by determining the change injoint position potentiometer reading versus the resistive load. Thiscalibration result may then stored in the microprocessor. When the handis extended by a prescribed pressure, the amount by which the extensionmotion is reduced from full extension is a measure of the resistingtorque.

In another aspect of the invention, protection against overloading alimb is provided by the compliant nature of the pneumatic muscle.Because of this compliance, it may not to be necessary to provide anauxiliary exhaust if excessive resistance is encountered. The compliancealso provides a method of measuring the resistive load, as confirmedthrough Mentor testing by means of a load cell inserted between the airmuscle and the actuating bar of the hand mechanism. A data acquisitionsystem recorded the load and the position as measured by the pivotpotentiometer at 100 Hz. Resistive forces were generated by hangingweights on the hand piece and also by wearing the Mentor and manuallyresisting the motion with different levels of force. The resistive loadversus the amount of extension is shown in FIG. 15. After one set ofresistive measurements was made, the initial tightness of the strapconnecting the bar to the load cell and the muscle was adjusted. Theload versus amount of extension is linear but is a function of theadjustment of the strap. Based on these results, the force sensing waschanged from force sensitive resistors (FSRs) to measuring the decrementfrom full extension. The load-rotation calibration of each Mentor isdetermined at the completion of assembly. These measurements alsodetermine the rate of extension.

The motion causing device 10 (i.e., the air-muscle) drives the fingersand wrist into extension by moving a mechanical linkage. The linkage isdesigned to move the fingers and/or wrist in a spiral fashion. Atherapist can also program the air-muscle(s) so that a desired motionpattern is followed for fastest and effective recovery.

Additionally, excessive force on the hand is prevented in several ways.A micro-compressor was chosen that has a maximum output pressure whichlimits the maximum force supplied by the air muscle. The air muscle is avery compliant drive with the maximum force output at the fully flexedposition where the stretch reflex resistance of the flexor muscles isminimum. As extension proceeds, the stretch reflex increases resistanceto motion. If a large resistance is encountered during extension, theair muscle stretches and limits the range of motion. Since spasticflexor muscles are velocity sensitive, the velocity of actuation waschosen to be about 5 degrees per second with no loading. With the weightof a flaccid hand this rate decreases to about 3.8 degrees per secondand with mild resistance the rate is approximately 2.7 degrees persecond. Previous experiments have shown only small increases in muscletone occurring for very spastic hemiplegics due to velocity at ratesbelow about 6 degrees per second. The rate in the present device isphysically controlled by the volume capacity of the micro-compressor andthe resistance in the pneumatic circuits. To prevent excessive extensionof the wrist, a physical stop may be provided that limits motion of theactivation bar at about 60 degrees of wrist extension. A safety panicswitch that releases the air pressure is also provided on a tether andis placed close to the patient's side.

An important aspect for choosing the actuator to be an air-muscle isthat the air-muscle permits relative motion between the proximal anddistal portions of the joint, due to its high mechanical compliance, ina manner that does not hinder or interfere with any motion generated bythe neuromuscular system. Allowing self-actuated motion of the joint bymeans of the neuromuscular system is an important element in the design.Specifically, the air-muscle allows unfettered self-actuated motion ofthe joint.

In another aspect of the invention, a continuous passive device, with ahigh mechanical compliance, that permits extension and flexion of thejoint through self-actuation could be used for neuromuscular functionreeducation and restoring physical function of the neuromuscular system.

FIG. 5 is a block diagram showing one embodiment of the present systemfor neuromuscular function reeducation and restoring physical functionof at least one neuromuscular system showing the controller 18 with amicroprocessor 44 and an electronic memory 50, the air-muscle 10, atleast one display 20, at least one joint position sensor 15, at leastone force sensor 48, at least one EMG sensor 14, at least oneneuromuscular electrical stimulation (NEMS) device 22 for providinglow-level neuromuscular stimulation. The real-time clock/calendar 52 ispowered by a battery mounted on the printed circuit board when the poweris off. The clock 52 maintains the time and date continuously. Recordsof patient use, active range of motion, extensor resistive torque, andEMG activity are recorded with a time stamp in a non-volatile serialEEPROM memory device 50. Data is kept safe, even when no power isapplied to the memory 50. These records can be downloaded to atherapist's or patient's personal computer. A patient record can beprinted that provides a performance history and compliance by date. Adisplay 20 is made available for viewing and monitoring joint/muscleactivity during therapy.

The microprocessor 44 controls the activation of the air muscle byoperating the microcompressor and/or the air valves. Wrist/jointposition may be displayed as a bar graph or as numbers on the LCDdisplay 20. The degree of flexor resistance torque measured by the atleast one force sensor, and/or electrical activity from the EMG sensormay be displayed as a variable length line of lit light emitting diodes(LEDs) incorporated next to the LCD display 20. The changing goal foractive wrist motion may be displayed as a line on the LCD graph. Oneline of multi-color light emitting diodes (LEDs) may indicate the degreeof flexor resistance torque as measured by the force sensitiveresistors. A second line of LEDs may indicate the EMG activity of thewrist or finger extensors. The microcompressor, air valves,microprocessor, and the LCD may be portably located on or beside thepatient during therapy sessions. Alternatively, feedback may be providedto the patient/therapist through audio signals (e.g., by varying thetonal frequencies, amplitudes, etc.). Records of patient use, activerange of motion, extensor resistive torque, and EMG activity arerecorded with a time stamp in an electronic memory device (e.g., anon-volatile serial EEPROM). The electronic memory system can providestored information, such as patient compliance and patient performance,from the electronic memory to a therapist/patient on command. Thus, thesystem includes a mechanism for the patient to monitor the complianceand performance through visual and possibly aural means. Moreover, thecontroller may update the displays in a predetermined manner to providea mechanism for the patient to improve performance and compliance forneuromuscular function reeducation and for restoring physical functionof the neuromuscular system in the patient.

The present invention provides neuromuscular reeducation and restorationof physical function of the neuromuscular system in the patient through(1) biofeedback, (2) repetitive task practice, and (3) neuromuscularelectrical stimulation (NMES). Furthermore, psychological research hasshown that an important part of biofeedback stimulated neuromuscularreeducation is shaping, which is defined by psychologists asestablishing goals just beyond current capability and changing goals asprogress is made. The present invention also provides shaping throughmeasurements obtained during therapy session. Additionally, research hasshown that many repetitions are necessary for permanent neuromuscularreeducation. To encourage practice of the repetitions, the presentinvention records compliance of a patient with the repetitive therapyand provides a report back to the patient's therapist.

One method for implementing a protocol, for the system as described, forrestoring physical function of the neuromuscular system comprisesmeasuring a signal indicative of the activity of the muscle through theEMG sensor(s) 14; measuring a signal indicative of the joint motionthrough a joint position sensor 15, where the joint is associated withthe neuromuscular system; measuring another signal indicative of themuscle resistance through the force sensor 48; mapping the measuredsignals to at least one parameter; and controlling the air level in theair-muscle 10 in order to optimize the parameter for restoring physicalfunction of the neuromuscular system associated with the joint in thepatient.

FIGS. 6, 7 depict one arrangement of pivot points 60 and linkages 64associated with the air-muscle 10 attached to forearm supports (asdepicted by 62). The air-muscle 10, upon inflation and deflation,permits the arm and joints to achieve pre-determined trajectories (shownas spiral type in the figures). Hence, the pivot point 60 positions andthe trajectories of the arm (or linkages 64) can be controlled byinflating/deflating the air-muscle 10 in a manner to get optimal motionfor the arm and joint thereby providing means for effective restorationof the physical function of the neuromuscular system. For example, inFIG. 6, the air muscle 10 is shown connected at one end to the forearmsupport 62 while at the other end it is depicted as being attached topivot point or driving point 60. When the air-muscle 10 isinflated/deflated in a specific manner optimal motion is achieved forreeducation and restoration of the neuromuscular system.

In an alternative embodiment, as depicted in FIGS. 10, 11, there is areduction in the number of linkages (over the embodiment of FIGS. 6, 7)but the muscle is still able to achieve the same trajectory and motion.

FIG. 8 is a flow chart depicting another embodiment of the protocol forrestoring physical function of the neuromuscular system. Specifically,the patient is instructed to try to extend the wrist when a beep isheard. The EMG activity of the wrist extensors and the motion of thewrist are recorded in the memory of the device and displayed for thepatient. The patient could be instructed to use the device for 6 hours aday, although more usage may be allowed, and the treatments need not becontinuous. The patient could start and stop the device at any time. Thefirst 2 hours could focus on EMG and joint position feedback. During thesecond 2 hours the flexor resistance torque from the flexors could beused as the feedback signal to help the patient reduce any flexorspasticity. The final 2 hours of therapy would include both extensor EMGand flexor resistance torque as feedback. The number of completed cyclescould be recorded for each day as well as the time for each cycle andthe total treatment time for each day. The patient could be encouragedto grasp a block and lift it several times during a day and at the endof each therapy session. After grasping, the patient may be encouragedto try and lift and subsequently move the block. The patient may also beencouraged to keep a record of successful attempts.

In the protocol, the level of extensor EMG activity may be indicated byLEDs on the display 20. A level equal to that obtained at the lastclinic therapy session would show as a yellow light. A level below wouldgenerate a buzzing sound. A green LED would indicate a higher level.Faster flashing LEDs indicate higher levels of EMG activity. The outputof the joint position sensor is displayed on the LCD by a bar. If motionexceeds this line a pleasant sound is heard. After every day, the linethat represents the goal could be increased/updated by a certain amount(e.g., 1% of the highest joint motion achieved in the previous day).Thus, joint position could serve as the basis for subsequent trainingeach day.

During training, whenever motion has stopped for a certain period (e.g.,3 seconds), the air-muscle could be activated and the wrist and fingerextension may be completed. The extension could be held for a certainamount of time (e.g., 3 seconds) and then released. The torque of theflexor resistance is measured and displayed on flashing red LEDs duringthe process (the higher the force, the faster the blinking). The patientcould be instructed to try to minimize this force by thinking aboutrelaxing the flexors. A system delay (for e.g., of about 10 seconds) maybe introduced and the process would be started over with an auditorybeep.

The number of hours of operation of the device and the active motionachieved at the beginning of a day and at the end of each day may berecorded in memory. This information would provide fairly accurateinformation about patient compliance and permits matching of timed datafrom patient reports of self-documentation of training. When the deviceis turned on for the first time each day, these parameters are displayedfor the patient on the LCD.

The memory may be downloaded onto a PC in the clinic. A summary chartgraphically displaying the number of hours of use a day by the patient,the range of motion change per day and the change of active range ofmotion day to day may be displayed and the charts printed for thepatient file.

In another aspect for providing therapy to a patient, the therapist canprescribe the patient as to how much time he or she can spend on aspecific program. In essence, the amount of emphasis on each programdepends on the symptoms of the patient. For example, the program couldrequire work on the extensor muscle recruitment. To this end, theextensor EMG signal may be displayed as a line of LED lights on arelative scale. Alternatively, a single color coded or intensity codedLED could be used. The range between the minimum and maximum signalmeasured may be about 60% of the height of the LED line. Messages may beprovided on the LCD display 20 to encourage the patient to increase thedisplay level.

A second program, that could be selected by the patient, includesmeasurement of the resistance offered by the flexor muscles (antagonistresisting muscles) to an extension process. It is common for patientswith neuromuscular diseases to develop a constant muscle contraction.Specifically, the flexors are substantially stronger than the extensorswhich causes the characteristic flexed fingers and wrist that can beseen in many patients. The reason for this is the lack of inhibitionpresent in the central nervous system. To retrain the neuromuscularsystem, the program could display the relative magnitude of the measuredresistance and request the patient to consciously try and reduce thesignal on the display. EMG sensors 14 located adjacent the flexormuscles and/or FSRs 48 or lack of full extension may be used formeasuring the resistance. The program may also require the patient toextend the wrist with the air muscle to about neutral position. At thispoint EMG activity or the force output of the FSRs may be measured forthe flexor muscles (antagonist resisting muscles). Subsequentcalculation of the active stiffness generated by the flexors may beachieved by dividing the measured force by the amount of jointdisplacement (as measured by the potentiometer 15).

A third program that can be selected for the patient permits (i)increasing the activity of the extensors, and (ii) simultaneouslydecreasing the activity of the flexors. The signal to one of the LEDlines may be a combination of the magnitude of the extensor signal, andthe flexor signal as measured either via the EMG sensor 14 or the FSR48. The patient may be asked to extend their fingers and wrist and thento think about their forearm so as to minimize the signal displayed viathe LED lines.

It is well established that continuous passive motion entails inducingmovement of certain limbs/joints without requiring muscle co-ordination,strength, or control by a patient. Numerous studies have shown that CPMof the different limbs and joints accelerates healing, and importantlyresults in a fuller range of motion of the joint at the end of thecourse of the therapy.

Thus, in another aspect of the system 200, as shown in FIG. 9, acontinuous passive motion (CPM) device 204, in conjunction with anair-muscle device 206 and 206′, may be used for providing flexion andextension to the joint 208 of the patient for reeducation andrestoration of the physical functions of the neuromuscular system in apatient. During extension, the upper air-muscle device 206 may becontrollably activated, whereas during flexion, the lower air-muscledevice 206′ may be controllably activated. By providing a controlledactivation of the air-muscle device in the CPM, it is possible toprovide reeducation and restoration of the neuromuscular system.

In another embodiment of the present invention the air-muscle ismodified so that it is capable of interacting with a personal computerbased virtual reality program for capturing the interest of the user.The resulting system allows extension of the existing wrist/hand devicethrough coordinated elbow and shoulder motions.

A prerequisite for the elaborate movements of the upper extremity, lowerextremity gait, and dexterous abilities of humans in general is theability to coordinate multiple joints and regulate forces produced bylimb segments. Research data indicate that patients with stroke exhibitdeficits in the ability to precisely control forces produced. However,with the air-muscle device, the inventors have found that this therapyimproves patients' ability to control grasping forces during a generalforce-tracking task and a functional task (e.g. turning a key in alock).

While the disturbance of voluntary upper extremity movement in patientswith stroke is typically apparent upon visual examination, little isknown about the mechanisms responsible for these disturbances due inpart to the dearth of quantitative studies of multi-joint movements insuch patients. During a target-directed pointing task, patients withstroke could reach into all parts of the workspace with their affectedlimb, suggesting that movement planning was intact for these patients.However, when inter-joint coordination was assessed by expressing elbowangle as a function of shoulder angle, patients with stroke exhibited anirregular and variable relationship. This disruption in inter-jointcoordination resulted in movement paths that were more segmented andvariable. It has been shown that prehension (reaching and grasping)movements of patients with stroke were characterized by a spatiotemporaldyscoordination between the arm and trunk. As a result, patientsdeveloped a new pattern of coordination represented by more trunkrecruitment during prehensile actions. More recently, a kinematicanalysis of reaching movements of patients with stroke indicated thatpatients with stroke, unlike healthy controls, recruited the trunk toassist in transporting the hand to the object. Thus, these patients wererecruiting a new degree of freedom (e.g. the trunk) to perform thistask. Further kinematic studies have shown that patients with strokehave a more variable: reaching path, orientation of the hand relative tothe object, final hand position on the object, and a disruption ininter-joint coordination. These data suggest that patients with strokehave difficulty with motor execution. Therefore rehabilitation of theaffected upper extremity with the air-muscle is oriented towardrestoring the normal sensorimotor relationships between the joints.

A consistent factor in laboratory and clinical studies ofneuroplasticity is that to obtain reorganization of the neural system,cognitive input must be present and many repetitions are required. Also,studies have shown that concentrating on the effects of their movementrather than specific body movements enhances the effect. In otherstudies, there is some evidence that training in only one or twocoordinated movements transfers to improvements in other tasks.

Therefore for the upper extremity, the therapeutic protocol chosen, forexemplary purposes according to one aspect of the invention, is to focuson two important tasks; reaching and eating. Specifically, the patientis requested to achieve either a reaching task or an eating task. Afterthe patient has achieved his/her maximal motion, the device assists thelimb to complete the task. Feedback of self-actuated progress isrecorded and fed back to the patient.

In summary, a critical review of rehabilitation approaches to reduceimpairments and improve upper extremity mobility among patientsfollowing stroke would lead to the conclusion that repetitive taskpractice incorporating biofeedback strategies can improve functional andmobility of patients with chronic stroke. When one adds to the growinglimitations on treatment time, it seems reasonable to speculate thattreatments emphasizing repetition of functionally-related tasks,performed in the home environment could enhance function and improvehealth related quality of life. This earlier relocation forcentralization of stroke therapy into the home appears effective inpromoting motor and functional gains while yielding substantial patientsatisfaction. Complementing this approach through inclusion of devicesthat reinforce the need for volitional activation of joint movementwhile concurrently offering knowledge of results about range of motion,muscle activity or resistance to movement could be beneficial if suchdevices were reliable, easy to use, cost-effective, and conducive tohome and clinical use.

FIGS. 12-14 shows various states of the air-muscle device used inconjunction with a robotic system for providing assistive training. Thedesign philosophy is such that it encourages volitional activation ofjoint movement through feedback range of motion, muscle activity andresistance to movement and then completing the task for the patient. Inone aspect, for exemplary purposes, the system is adapted to providetraining of two tasks (viz., feeding and reaching). It is anticipatedthat training of coordinated joint movement for these two tasks willlead to more general improvement in related functional tasks as found inother feedback therapies.

To train for the reaching motion, the robot system abducts the shoulderin the flex direction, extends the elbow, supinates the forearm, andextends the wrist and fingers. Training begins with the patient facing atable with her/his forearm resting on the table transverse to the torso(in a plane parallel to the frontal plane) as shown in FIG. 12. In oneaspect of the invention, the shoulder motion is restricted to flexion inthe sagittal plane. Thus, the intermediate reaching position is shown inFIG. 13.

To train for an eating motion, the robotic system flexes the shoulder,supinates the forearm, and extends the wrist as shown in FIG. 14. Moststroke patients have the ability to flex their elbow, so this functionmay be left to the patient. The assisted movements may be made in a slowmanner to protect against significant increases in muscle tone.

Thus, as shown in the FIGS. 12-14, the air muscle 500 rotates theshoulder in abduction and flexion. A plastic hinge 502 only allowsmotion in the sagittal plane. The normal internal rotation of thehumerus is held in neutral by the distal and proximal strapping system.The proximal air muscle rides on a plate 504 that rotates about thecenter of rotation of the humerus. A foam-lined sub-plate 506, that isattached to the torso with Velcro straps, distributes the verticalreaction of the air muscle. A plastic cuff 508 is attached to the upperhumerus with Velcro straps. This serves as an attachment point for adriver 510 that is connected at its other end to the sliding plate thatrests on top of the sub-plate. Contraction of the air muscle rotates theupper plate 504 in an arc about the center of rotation of the humerus. Apotentiometer (not shown) centered on the axis of rotation records theamount of shoulder motion.

To control elbow motion, a hinge (not shown) is attached at the elbowwith straps to the distal humerus and proximal forearm. A potentiometeris contained in the center of rotation of the hinge to measure elbowflexion and extension. The forearm piece 512 has an extension 514 thatis used an attachment point for an air muscle. The proximal end of thisair muscle is attached to the center of rotation of the humerus.

Supination/pronation, plus coordinated extension of the wrist andfingers is obtained by a modification of the wrist/hand device that hasbeen clinically tested and currently is in commercial distribution. Twomuscles are attached to the hand/wrist device. The proximal end of oneis attached to the inside of the forearm at the elbow and the otherproximal end of the other one is attached to the outside of the forearmat the elbow. If the latter muscle is contracted, combined wrist andfinger extension occurs along with supination of the forearm. If theother muscles contracts, combined wrist and finger extension occursalong with pronation of the forearm. A potentiometer is located at thecenter of rotation of the wrist. Initially, no measurement ofpronation/supination will be included.

The above described system and programs thus provide effective and easyto use functionality for reeducation and restoration of the physicalfunctions of the neuromuscular system in a patient. The system isinexpensive, portable, comfortable, and easy to use either by thepatient or by a therapist.

In summary, the system and method according to the present invention isa self-contained, mobile device, implementing a protocol, and whichprovides visual and/or aural feedback of wrist and finger position,measurement of extensor and flexor activity for neuromuscular functionreeducation and restoring physical function of at least oneneuromuscular system in a patient.

The attached description of exemplary and anticipated embodiments of theinvention have been presented for the purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many modifications andvariations are possible in light of the teachings herein. For example, asuitable inflatable device or mechanical drive can be used inreplacement for the air-muscle. Additional sensors could be used formeasuring critical parameters for restoring physical function. Multiplemotion causing devices could be simultaneously connected at variouspositions on the patient's body, and the devices could be controlled bymultiple or single controllers. Also, there could be a single displayconfigured to provide feedback on several different measured parameters.The therapist could be allowed to select, from a menu provided throughthe display, unique therapeutic protocol(s) for a specific patient.Furthermore, the frequency of patient use and the ability to reachperformance goals can be recorded in memory and the record played backfor the therapist/patient. While the specification describes particularembodiments of the present invention, those of ordinary skill can devisevariations of the present invention without departing from the inventiveconcept.

1. A system for assisting neuromuscular function comprising: at leastone EMG sensor for detecting self-actuation of a neuromuscular system;at least one joint position sensor for detecting self-actuation of ajoint; at least one force sensor for measuring a parameter indicative ofmuscle resistance; a computer processor for implementing a protocolresponsive when self-actuation or attempted self-actuation is detectedby the at least one EMG sensor and is not detected by the at least onejoint position sensor; and a motion causing device for assisting the atleast one joint in movement, said motion causing device following theprotocol implemented by the computer processor.
 2. The system of claim 1further including an electronic memory system for storing informationregarding the patient.
 3. The system of claim 2 wherein the protocol isbased on previous measurements recorded from at least one of the EMGsensor, joint position sensor, and force sensor.
 4. The system of claim1 further including at least one neuromuscular electrical stimulating(NMES) system for providing neuromuscular stimulation to the at leastone neuromuscular system.
 5. The system according to claim 1, whereinthe motion causing device is an air-muscle.
 6. The system according toclaim 1, wherein the air-muscle includes at least one port for supplyingpressurized air to inflate said air-muscle.
 7. The system according toclaim 6, wherein the computer processor controls at least one valve forcontrolling the supply of pressurized air to the air-muscle.
 8. Thesystem according to claim 1, further including a first display fordepicting the electrical activity from the EMG sensor.
 9. The systemaccording to claim 8, further including a second display indicating adegree of flexor resistance torque measured by the at least one forcesensor.
 10. The system according to claim 9, wherein the displaysprovide a means for the patient to monitor the compliance andperformance.
 11. The system according to claim 10, wherein thecontroller updates the displays in a predetermined manner to provide amechanism for the patient to improve said performance and saidcompliance.